Twice now I have booked a flexi fare for a Virgin domestic flight on line and both times when I've tried to upgrade using points it say an upgrade is not available on the fare basi

Twice now I have booked a flexi fare for a Virgin domestic flight on line and both times when I've tried to upgrade using points it say an upgrade is not available on the fare basis. It used to be no problem. Has anyone else come across this?

I suggest you call the service centre to book. I get them to make sure it's available & then book & get it all done at once.

The procedure to do this should always be:

Log in to VFF first to see if any reward seats on your desired flight are available. Then set up your booking online and continue on to the point where you are about to pay. Then call VFF and get them to check for upgrade availability. If they say yes, tell to them to wait a moment while you pay for the booking - then give them the PNR and they process the upgrade. If not, try different flight, etc. 

I've had that a few times, but as it's a flexi I've been able to call them to find another suitable flight on the same day that works for me, switch for no fee then ask them to upgrade me while I'm on the phonel. I've had it on 737 flights, never on an A330.